In recent years, popularization of electric vehicles is greatly expected, for countermeasures against global warming. The electric vehicles are required to be charged even if a user is in a house or out the house. At this time, connection to a power line is made via a charging cable. However, there is a risk of an unauthorized charge in power outlets outside the indoor for making a connection to the electric vehicles. Therefore, mutual authentication is required at both sides of a power feeding side and a power charged vehicle side.
Further, in recent years, a power line communication is promoted, for transmitting data by superimposing a PLC (Power Line Communication) signal (2 to 30 MHz) having high frequency, being an information signal, on a signal having a commercial frequency (50 to 60 Hz) transmitted to a power line. For example, various information communications through charging external equipment, charging terminals, and charging cables, and various services utilizing the authentication, are expected. Meanwhile, a risk of invading into a PLC network from outside of the indoor is increased, and therefore a technique of separating and unifying a passage of signals of a power line is required.
Therefore, a technique of suppressing the passage of the signals in the power line communication is reported as follows.
For example, in the power line communication system described in (Patent document 1), a blocking filter for suppressing signals of the power line communication without interfering with transmission of power of commercial alternating currents, is provided on an indoor distribution line in each group of a power line communication system that constitutes a local area network of a plurality of groups. The blocking filter has a core formed by a magnetic material, and the signals of the electric power line communication are suppressed by passing or winding electric paths of the indoor distribution line, so that a magnetic flux is generated in the same directions in the core by a simultaneously flowing current, with these electric paths set as a travel road and a return road.